Slope Mower With PTO-Related Safety Features

ABSTRACT

Mowing systems include a mower and, optionally, a remote control unit such as a handheld unit, between which may be provided 1- or 2-way communications. Components and features are included in the mower, the remote control unit, or both to enhance the safety, functionality, or user experience of the system&#39;s user/operator. One aspect relates to monitoring a tilt angle of the mower, and defining or executing different system responses as a function of different first and second conditions that relate to the tilt angle. Another aspect relates to automatic adjustment of a speed setting of the mower&#39;s drive system as a function of a power takeoff (PTO) unit of the mower.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. Ser. No. 16/530,873, “Slope Mower WithSafety Features”, filed Aug. 2, 2019 and now issued as U.S. Pat. No.11,240,966 (Brandt), the contents of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to systems for mowing grass, weeds, brush,and the like, with particular focus on such systems that allow the mowerto be controlled remotely e.g. using a handheld unit or other remotecontrol unit, as well as systems in which the mower is adapted for useon moderately- to highly-sloped terrain surfaces. The invention alsopertains to related methods, systems, and articles.

BACKGROUND OF THE INVENTION

Numerous types of residential, commercial, and industrial mowing systemsare known. The vast majority of such systems are configured for manualcontrol by a single user who pushes, or in some cases sits atop, a mowerunit. The vast majority of such systems are also configured for use onterrain that is flat or gently sloped, e.g. for terrain whose slopeangle may range from 0 degrees (flat and level) to 22 degrees.Furthermore, many known riding mowers are equipped with separateleft-wheel and right-wheel control handles by which the user can movethe mower forward, reverse, and through a range of turns, includingforward turns, backward turns, and so-called zero-turns, i.e.,maneuvering the mower through a turn whose turn radius is essentiallyzero.

There are also some known mowing systems that employ a remote controlunit to maneuver and control the mower from a distance, as well as somethat employ a mower specially designed to operate on terrain whose slopeangle is greater than 22 degrees, such mowers known in the art as “slopemowers”. See for example U.S. Pat. Nos. 7,677,344 (Medina et al.) and8,634,960 (Sandia et al.).

SUMMARY OF THE INVENTION

Slope mowers and systems that employ them have unique operational andfunctional challenges due to the elevated dangers and difficultiesassociated with sliding, falling, overturning, and maneuvering onsteeply sloped terrain. Remotely controlled mower systems also havetheir own operational and functional challenges, such as how to preventa powerful cutting device that has its own source of locomotion fromlosing control or otherwise jeopardizing the safety of the user/operatoras well as bystanders. The present inventors have recognized a need forincorporating new, innovative features to mower systems especiallyremotely controlled slope mower systems that can enhance the safety,functionality, or other utility of the system. The disclosedenhancements satisfy one or more of those needs and form the basis fornew families of remote-control mower systems and methods, and othermower systems.

This document actually discloses a number of such enhancements, each ofwhich is described in more detail below. The enhancements may beimplemented individually in a given mower system, or in combinations asdesired. One aspect relates to monitoring a tilt angle of the mower, anddefining or executing different system responses as a function ofdifferent first and second conditions that relate to the tilt angle.Another aspect relates to automatic adjustment of a speed setting of themower's drive system as a function of a power takeoff (PTO) unit of themower.

One aspect relates to a mower that includes a frame, an engine attachedto the frame, mower blades attached to the frame and selectively coupledto the engine by a power takeoff (PTO) unit, a controller configured toseparately control the PTO unit and the engine, and an inclinometerattached to the frame and coupled to the controller, the inclinometerproviding an. inclinometer output indicative of a tilt angle of theframe. The controller may be configured to turn the PTO unit off butkeep the engine on when the inclinometer output satisfies a firstcondition, and configured to turn the engine off when the inclinometeroutput satisfies a second condition.

Another aspect relates to a mower that includes an engine, a powertakeoff (PTO) unit, a controller configured to separately control thePTO unit and the engine, the controller including a central processingunit (CPU) and a memory unit in which instructions are stored, and aninclinometer coupled to the controller, the inclinometer providing aninclinometer output indicative of a tilt angle of the mower. Theinstructions may be configured to turn the PTO unit off but keep theengine on when the inclinometer output satisfies a first condition, andconfigured to turn the engine off when the inclinometer output satisfiesa second condition.

Another aspect relates to a method of operating a slope mower having anengine, a power takeoff (PTO) unit, an inclinometer, and a controllerconfigured to separately control the PTO unit and the engine. The methodmay include turning the PTO unit off but keeping the engine on when anoutput of the inclinometer satisfies a first condition, and turning theengine off when the output of the inclinometer output satisfies a secondcondition.

Another aspect relates to a mower that includes an engine, a PTO unit, adrive system, and a controller. The drive system may include a leftdrive wheel, a right drive wheel, a left actuator, and a right actuator,the left actuator having a position that controls a speed of the leftdrive wheel, and the right actuator having a position that controls aspeed of the right drive wheel. The controller may be coupled to the PTOunit and to the left and right actuators of the drive system, and may beconfigured to provide first drive signals to the first and secondactuators when the PTO unit is off, and second drive signals to thefirst and second actuators when the PTO unit is on, the first drivesignals characterized by a first maximum drive speed and the seconddrive signals characterized by a second maximum drive speed, the secondmaximum speed being less than the first maximum speed.

Numerous related methods, systems, and articles are also disclosed.These and other aspects of the present disclosure will be apparent fromthe detailed. description below. In no event, however, should the abovesummaries be construed as limitations on the claimed subject matter,which subject matter is defined solely by the attached claims, as may beamended during prosecution.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive articles, systems, and methods are described in furtherdetail with reference to the accompanying drawings, of which:

FIG. 1 is a schematic perspective view of a slope mower and a remotehandheld unit, forming a slope mower system;

FIG. 2 is a schematic side view of a mower operating on sloped terrain,thus in a tilted state;

FIG. 3 is a schematic side view of a remote handheld unit in a tiltedstate;

FIG. 4 is a perspective view of a coordinate system showing how a tiltvector or tilt angle can be decomposed into component tilt angles inorthogonal coordinate planes;

FIG. 5 is a schematic block diagram of a mower;

FIG. 6 is a schematic bottom view of a mower;

FIG. 7 is a schematic perspective view of a mower deck portion of amower;

FIG. 8 is a schematic block diagram of a remote handheld unit;

FIG. 9 is mode transition diagram for a mower system;

FIG. 10 is a schematic block diagram of a mower system;

FIG. 11 is a transition diagram for a safety interlock;

FIG. 12 is a schematic top view of a joystick for use on a remotehandheld unit;

FIG. 13 is a perspective view of a spherical coordinate system showinghow an arbitrary orientation of the joystick can be expressed by a polarangle ϕ and an azimuthal angle θ;

FIG. 14 is a planar representation of the (ϕ, θ) coordinate system; FIG.15 is a representation similar to that of FIG. 14, but with pairs ofwheel or track speed arrows superimposed thereon;

FIG. 16 is a representation similar to that of FIG. 15, but where nullpoints have been shifted to provide enhanced fine control capabilities;

FIG. 17 is a graph of relative wheel speed versus joystick angle θ, at afixed polar angle ϕ, for both standard operation and enhanced finecontrol operation;

FIG. 18 is a graph similar to that of FIG. 17, but where the polar angleϕ is fixed at ϕmax/2;

FIG. 19 is a graph similar to the standard operation curve of FIG. 17,but where a spin function modification has been applied to providebetter zero-turn user control;

FIG. 20 is a graph similar to the enhanced fine control operation curveof FIG. 17, but where the spin function modification has been applied;

FIG. 21 is a schematic flow diagram showing a process for transformingjoystick transducer values to actuator drive signals;

FIG. 22 is another schematic block diagram of a mower system, showingsome elements relevant to speed control;

FIG. 23 is a graph of relative mower speed versus joystick angle ϕ,showing curves for various speed control settings;

FIG. 24 is another schematic block diagram of a mower system, showinghow mower tilt angle can be displayed on the remote handheld unit;

FIG. 25 is a schematic flow diagram showing a process for calculatingand displaying a tilt angle of the mower on the remote handheld unit;and

FIG. 26 is a schematic block diagram of a mower system, showing howdiagnostic information can be shared between mower and handheld unit,and displayed or otherwise communicated to the user.

In the figures, like reference numerals designate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

We have developed new families of remote-control slope mowing systemsand methods. Embodiments thereof may use or include one or more of theinnovative ideas and features discussed further below to enhance thesafety, functionality, or other utility of the system. Most if not allof the innovative features are of particular utility in slope mowingsystems configured for remote control operation, but the reader willappreciate that many can also be applied to other types of mowingsystems, including in some cases mowing systems that are not remotelycontrolled, and mowing systems in which the mower is not a slope mower.Of the various different features or enhancements described herein, agiven mowing system may incorporate only one such feature, or only twosuch features, or any combination of such features.

A schematic diagram of a representative mowing system 110 is shown inFIG. 1. The system 110 is made up of two main subsystems or units: amower 120, and a remote control unit 160. These two units communicateaccording to at least a 1-way protocol from the remote control unit 160to the mower 120 to allow a user to control the operation of the mower120 by manipulating input device(s on the unit 160. For many of thedisclosed enhancements, however, 2-way communications are necessary orat least desirable as explained further below. Hence, FIG. 1 depictsboth mower-generated signals 114 and remote control unit-generatedsignals 116 The mower 120 may thus include, besides one or moreantennas, a signal generator, transmitter, receiver, transceiver, orother electronic device(s) capable of generating the mower's outgoingsignals 114 and detecting the incoming signals 116 from the remotecontrol unit 160. Likewise, the remote control unit 160 may include asignal generator, transmitter, receiver, transceiver, or otherelectronic device(s) capable of generating the unit's outgoing signals116 and detecting the incoming signals 114 from the mower 120.

The communication devices used in the mower 120, in the remote controlunit 160, or in both may transmit and receive electromagnetic radiationwirelessly in any suitable frequency/wavelength band. Typically, radiofrequency (RF) radiation, more particularly the microwave band (0.3GHz-300 GHz), and more specifically the ultra high frequency (UHF) band(0.3 GHz-3 GHz) are of particular utility. One example of a suitable REfrequency is 2.4 GHz. In other cases, higher RF frequencies can be used,such as the super high frequency (SHE) band (3 GHz-30 GHz) in which cellphone communication systems operate. In other cases, optical ornear-optical frequencies, such as emitters and receivers operating inthe far-, mid-, or near-infrared band, may be used. The particularfrequency or frequency band chosen for the wireless communications forthe system 110 will determine the optimal design details of whatantenna(s) or other emitting or detecting devices are to be used in themower 120 and in the remote control unit 160.

In FIG. 1 the mower signals 114 are shown propagating towards the remotecontrol unit 160, and the signals 116 are shown propagating towards themower 120, but in most cases an antenna will broadcast signals insubstantially all directions. In this regard, although wirelesscommunications may occur directly between the mower 120 and the remotecontrol unit 160 as suggested in FIG. 1, the communications mayalternatively occur indirectly with the addition of one or more othertransmit/receive devices. For example, communication devices in themower 120 may communicate with a nearby cell phone tower (not shown) orother communication hub, and communication devices in the remote controlunit 160 may communicate with the same communication hub, thusestablishing indirect but actual communication between the remotecontrol unit 160 and the mower 120 by way of the communication hub.

The mower 120 may be configured as a slope mower as shown in FIG. 1. Assuch, it may have a track base (or wheel base) that is wide enough, anda profile or height that is low enough, to allow it to operate on slopesgreater than 22 degrees without undergoing unsafe slides, falls,turnovers, or the like. For reference purposes we may define a localcoordinate system whose orientation is fixed to the body of the mower120 to help describe the orientation of the mower 120 relative to itssurroundings. See in this regard the Cartesian x-y-z coordinate systemof FIG. 1, where the y-axis defines back-to-front, the x-axis definesside-to-side, and the z-axis is along the height of the mower.

The remote control unit 160 may be sized and otherwise configured to becarried by the operator/user who uses it to operate the mower 120 from asafe distance. The unit 160 may thus for example have a size, weight,and shape that allow it to be easily carried by a typical operator/userwhile the user walks about on or near the terrain to be cut. The unit160 may be configured with left and right handles for grasping by theuser's hands, or with a strap for hanging about the user's neck, or witha strap for attaching to the user's waist, or with any two or all threeof these features. In any such case, due to its mobile design, we mayrefer to the remote control unit 160 alternatively as a remote handheldunit, or more simply as handheld unit 160 or handheld 160. For referencepurposes we may define a local coordinate system whose orientation isfixed to the body of the handheld unit 160 to help describe theorientation of the handheld unit relative to its surroundings. Althoughnot shown in FIG. 1, such a local coordinate system is shown in FIG. 3.

The proximity or distance between the mower 120 and the handheld 160 islabeled in FIG. 1 as distance D. This distance will be discussed furtherbelow in connection with a safety feature that employs proximity devicesin both the mower 120 and the handheld 160. The distance D may bemeasured or expressed either in standard units such as inches, feet, ormeters, or in relative or non-standard units.

A slope mower 220, which may be the same as or similar to mower 120, isshown in FIG. 2 in the context of an idealized terrain 212 on whichgrows grass, brush, or the like (not shown). The terrain 212 has a flat,level portion adjacent a portion 212 a that is sloped at a constantangle a (alpha) relative to an earth-centric horizontal plane. A localx-y-z coordinate system 221 is referenced to the mower 220 in similarfashion to the local coordinate system described above. As a result ofthe mower 220 being situated on the sloped terrain 212 a, the localcoordinate system 221 is tilted by the same angle α, as measured betweenan earth-centric vertical axis v and the z-axis (height direction) ofthe mower 220. In the depicted orientation of the mower 220, the tiltangle α is in the y-z plane. If the mower 220 were rotatedcounterclockwise by 90 degrees about the z-axis, the tilt angle α wouldbe in the x-z plane of the local coordinate system.

A remote control unit or handheld unit 360, which may be the same as orsimilar to the previously described unit 160, is shown in FIG. 3. Thehousing of the unit 360 has openings on opposed sides thereof which formleft and right handles 365 in the adjacent housing wall. The unit 360may have a panel that divides the housing into a lower, closedcompartment 363L and an upper, open compartment 363U. Knobs, switches,buttons, joysticks, and other user input devices may be mounted to thepanel for access by a user. The user may touch and manipulate such userinput devices by reaching with hands or fingers through the large topopening in the housing into the upper compartment 363U. Delicateelectronic circuits and components, and batteries, may be mounted andhoused in the lower compartment 363L, which may also be sealed to bewater-tight. The unit 360 is shown in a tilted state for reasons thatwill become apparent in the discussion below. A local x-y-z coordinatesystem 361 is referenced to the handheld unit 360, with the y-axisoriented back-to-front, the x-axis oriented side-to-side, and the z-axisalong the height of the unit's housing. The unit is shown tilted in thex-z plane by a tilt angle α, as measured from an earth-centric verticalaxis v. If the unit 360 were rotated clockwise by 90 degrees about thez-axis, the tilt angle α would be in the y-z plane of the localcoordinate system.

The tilt orientations shown in FIGS. 2 and 3 are somewhat idealizedinsofar as the tilt is shown to occur entirely in the x-z plane or they-z plane of the local coordinate system. In general, the tilt directionas measured by the position of the earth-centric vertical axis vrelative to the local coordinate system will be more complex, neitherlying entirely in the x-z plane nor lying entirely in the y-z plane. Thedistinction can be significant from a practical standpoint if aninclinometer device is used that only provides tilt measurements in themajor (x-z and y-z) planes. Stated differently, if an inclinometerdevice is employed that provides a first tilt measurement in the x-zplane and a second tilt measurement in the (orthogonal) y-z plane, atransformation must be applied to convert those component measurementsto a net tilt angle α. FIG. 4 illustrates how a randomly oriented tilt,having a net tilt angle α relative to the z axis of the local coordinatesystem of a mower or handheld unit, is decomposed into component tiltangles α1, α2 in the orthogonal x-z and y-z planes, respectively, Fromthe Pythagorean theorem we know that:

sin²(α)=sin²(α1) sin²(α2)

Hence, the net tilt angle α of the mower or the handheld unit can bedetermined from the measured component tilt angles α1, α2 as follows:

α=sin⁻¹(sqrt(sin²(α1)+sin²(α2)))

Turning now to FIG. 5, we see there a schematic block diagram of a mower520, which may be the same as or similar to previously described mowers120, 220, and which may be a slope mower. The mower 520 has a localx-y-z coordinate system 521 as described above. The mower includes amain body 522 which is propelled by left and right continuous tracks523L, 523R. The tracks provide added stability and traction on steepinclines compared to individual wheels, but may if desired be replacedby wheels. The tracks can be driven in a forward or reverse mode by leftand tight drive wheels 524L, 524R as shown. The wheels 524L, 524Rreceive their turning torque from left and right transaxies 528L, 528Rby way of hydraulic transmissions 526L, 526R and drive axles 525L, 525R.Thus, a given drive wheel 524L, 524R will engage its respective track523L, 523R to move the mower 520 only to the extent mechanical torqueand rotational motion is transmitted from the transaxle 528L, 528R tothe drive wheel by the transmission 526L, 526R. In a neutral position,these transmissions transmit no torque or motion to their respectivedrive wheels, such that the mower remains stationary. In a forwardposition, a given transmission transmits torque and motion from itstransaxle to its drive wheel to move the mower forward, while in areverse position, torque and rotational motion is transmitted to thedrive wheel to move the mower backward. Mechanical control of thetransmissions is accomplished by respective left and right linearactuators 524L, 524R which mechanically engage their respectivehydraulic transmissions 526L, 526R. A neutral position of a givenactuator corresponds to the neutral position of the transmission, and nomotion of the associated drive wheel. Positive displacement of theactuator engages the transmission to provide forward motion of the drivewheel, with increased positive displacement yielding increasedtransmission engagement and increased (forward) drive wheel speeds.Negative displacement of the actuator engages the transmission toprovide reverse motion of the drive wheel, with increased negativedisplacement yielding increased transmission engagement and increased(reverse) drive wheel speeds. Independent control of the left and righttransmissions via the left and right actuators can thus produce a fullrange of motion of the mower 520, from straight forward over a range ofspeeds (both drive wheels and tracks moving forward at the same speed),to straight backward over a range of speeds (both drive wheels andtracks moving backwards at the same speed), to a range of turns fromgradual to sharp to zero-turn (drive wheels moving at different speedsand/or in different directions).

The transaxles 528L, 528R are powered by a suitable engine 530. Theengine 530 may be an internal combustion engine powered by gasoline orother suitable fuels supplied to the engine from fuel tanks 531L, 531R.Since the mower may operate in a highly tilted orientation for extendedperiods, it is advantageous to mount the fuel tanks on opposite sides ofthe engine so that gravity-induced fuel feed will occur from at leastone of the tanks for any given mower orientation. The engine 530 may beequipped with a choke 535, throttle 536, oil pressure gauge 537, andelectronic starter 538, among other accessories.

The engine 530 also engages or drives a power takeoff (PTO) unit 532.The PTO unit serves the function of selectively coupling the engine tothe mower blades, examples of which are seen in FIG. 6. Thus, in an ONstate, the PTO unit 532 couples the engine to the blades to rapidly spinor rotate the blades and thus cut the grass, weeds, brush, or othervegetation located beneath the mowing deck. In an OFF state, the PTOunit 532 decouples the engine from the blades, causing the blades toremain stationary, thus leaving the underlying vegetation uncut.

The mower 520 also includes a controller 534 which electronicallycontrols or communicates with many other system components over wiredconnections, including the actuators 527L, 527R, the choke 535, throttle536, oil pressure gauge 537, and starter 538, and. the PTO unit 532. Thecontroller 534 also preferably electronically communicates with anon-board memory 539, inclinometer 540, horn 541, light(s) (discrete orgrouped) 542, antenna 544, proximity device 546, and brake 547. Thecontroller 534 may be any suitable digital electronic controller ormicrocontroller, now known or later developed, that is capable ofperforming the tasks described herein in the hot, noisy, andhigh-vibration environment of an engine-powered mower. The controller534 may include one or more suitable central processing unit (CPU),system clock, dedicated read-only memory (ROM) and random access memory(RAM), and input/output modules, among other features and capabilities.The controller 534 may be or include a single integrated circuit (IC) orcircuit board, or it may include multiple such circuit boards and ICs.The separate memory 539 may be or include non-volatile memory, and itmay store instructions such as software and firmware which, when loadedinto and carried out by the controller 534, cause the controller andmower to perform the tasks described herein. The reader will understandthat an electronic engineer of ordinary skill can select the appropriateelectronic components and configure them in such a way as to provide thecontroller 534 and the mower 520 with the functionality as described,without undue experimentation.

In addition to sending control signals to the various components itmanages, the controller 534 may also receive diagnostic informationincluding sensor information or other status information from suchcomponents. Thus, the wired link between the controller 534 and a givenone of the actuators 527L, 527R may allow for both (a) control signalsto be sent from the controller to the actuator to cause the actuator tomove to the desired position, and (b) diagnostic signals or statusinformation to be sent from the actuator to the controller. Thediagnostic signals may for example include one or more actuator faultsignals generated by one or more fault sensors that may be included aspart of the actuator, or as part of the controller 534, or as an add-onaccessory. In exemplary embodiments such a fault sensor may be orinclude an open circuit detector or a short circuit detector, or both,which monitors electrical continuity between wires or pins of a givenactuator. Similarly, the wired link between the controller 534 and thePTO unit 532 also may allow for both (a) control signals to be sent fromthe controller to the PTO unit to turn the PTO unit ON or OFF, and (b)diagnostic signals to be sent from the PTO unit to the controller. Thediagnostic signals may for example include one or more PTO output errorsgenerated by one or more fault sensors that may be included in, or addedto, the PTO unit, or that may be part of the controller 534. Again, suchfault sensor may be or include an open circuit detector or a shortcircuit detector, or both, which monitors electrical continuity betweenwires or pins of the PTO unit. Similar comments and capabilities applyto other components coupled to the controller 534, such as the choke535, the throttle 536, the oil pressure gauge 537, the inclinometer 540,the horn 541, the lights 542, the proximity device 546, and the brake547. Thus, for example, the controller 534 may have one or morededicated circuits or elements that monitor the electrical continuity ofany or all of these components, and detect an electrical short orelectrical open circuit condition. In some cases the fault sensor mayalso be or include a. voltage or current sensor, e.g. to monitor outputcharacteristics of the battery 548.

The inclinometer 540 may in some cases be omitted from the mower 520unless the tilt-related capabilities described herein are of interest.The inclinometer 540 may be simple in design and function, or it may bemore sophisticated and complex. In some cases the inclinometer mayinclude two or more distinct, e.g. 1-axis, inclinometers. In some casesthe inclinometer may be or include a simple switch that is activatedwhen a tilt angle (whether a net tilt angle or a component tilt angle ina given plane) exceeds a preset angle, or a plurality of such switchesoriented along different planes of tilt, or a plurality of such switcheshaving different preset angles. In preferred embodiments theinclinometer 540 provides to the controller 534 an analog or digitalelectronic output signal that represents the actual tilt angle componentin a given plane, or the actual net tilt angle, to a fairly high degreeof precision, e.g. in increments of 1 degree, or 0.5 degrees, or 0.1degrees. Stated differently, the inclinometer preferably provides anelectronic output signal that is representative of an actual net tiltangle, or one or two actual component tilt angles, and substantiallycontinuously variable over a range of angles, e.g. from 0 to at least30, 40, 50, 60, 70, or 80 degrees.

The antenna 544 functions at a minimum to detect electromagnetic signalsbroadcast by the handheld unit, whether directly or indirectly. Directdetection involves detecting the handheld-emitted signals such assignals 116 without any intermediary detection and rebroadcast. Indirectdetection involves detecting not the handheld-emitted signals 116themselves, but a rebroadcast of such signals, the rebroadcast in someembodiments occurring at a different region of the electromagneticspectrum than that of the original signals 116. If direct detection, andthus direct communication between the mower antenna 544 and that of thehandheld unit, is used, the antennas preferably operate in the UHF bandof the electromagnetic spectrum. If indirect detection and indirectcommunication between the mower and the handheld unit is used (e.g.where the units communicate at standard cell phone frequencies using acell phone tower), the antennas preferably operate in the SHF band.Signals from the handheld unit that are detected by the mower antenna544 may include information relating to the status (including change ofstatus) of knobs, switches, buttons, joysticks, or other devices(including user input devices) that are included in the handheld unit,and may specifically include handheld unit inclinometer information andhandheld unit diagnostic information.

In many embodiments the antenna 544 not only detects signals broadcastby the handheld unit, but also broadcasts mower signals 514 forreception by the handheld unit. In such cases, the mower signals 514emitted by the antenna 544 may include, for example, mower inclinometerinformation and mower diagnostic information. The antenna 544 is shownschematically in the figure as a single antenna structure, and so it maybe, but it may also be or include two or more antenna structures, e.g.one for receiving incoming signals and one for emitting or broadcastingoutgoing signals.

The proximity device 546 may be or include a beacon, adistance-measuring device, a position-measuring device, or anycombination thereof. A beacon is simply an electromagnetic emitter thatdoes not itself measure distance or position, but whose output signalcan be used by another device, such as a second proximity device on thehandheld unit, to determine distance or position. A distance-measuringdevice can determine or measure a distance to another object, such as toa distant, external beacon or a second proximity device on the handheldunit, but cannot determine a direction to such other object, and thus itcannot determine the position of such other Object, nor its own positionrelative to such other object. A position-measuring device can determineor measure the position of another object, such as an external beacon ora second proximity device, or the position of itself relative to suchother object, and thus it can also determine or measure the distance tosuch other object. An example of a position-measuring device is a globalpositioning system (GPS) device.

The mower 520 may of course also include one or more batteries 548 tosupply the electrical power needs of the starter 538, controller 534,actuators 527L, 527R, and other electronic components of the mower. Thebattery 548 may be rechargeable, or non-rechargeable.

A bottom view of a mower 620, which may be the same as or similar tomower 520, is shown in FIG. 6. The mower 620 has a main body 622 andleft and right continuous tracks 623L, 623R which can turn forward andbackward independently of each other at controlled speeds to propel themower 620 forward, backward, or through various types of turns,including zero-turns. The mower 620 has a local x-y-z coordinate system621 as described above. The main body 622 includes a welded metal frame650 for structural support and integrity, and to which other componentsare mounted or attached. A mower deck 651 is also included, which housesthe cutting blades (mower blades) 652. In the depicted embodiment threerotating blade assemblies are shown housed in the mower deck 651, but inother embodiments only one, or only two, or more than three suchassemblies may be used as desired. The mower blades 652 are mechanicallycoupled to the PTO unit, which in turn couples to the mower engine (seeFIG. 5). When the PTO unit is ON, the engine causes the mower blades tospin rapidly and cut the grass, weeds, or other vegetation under themower deck. When the PTO unit is OFF, the mower blades remainstationary.

One or more smaller wheels 653 may also attach to the mower deck 651 foradded support and stability. The mower 620 also preferably includesconventional mechanisms (not shown) to adjust the height of the mowerdeck 651 relative to the ground (terrain) so the user can adjust thegrass cut length as desired. The height-adjustment mechanism(s) may bemechanically adjustable by hand, or may be pneumatically, hydraulically,or electronically adjustable, and as such may also be remotelyadjustable via a user input device on the handheld unit.

At the front of the mower 620, flying debris may be propelled outwardfrom the gaps between the deck wheels 653 during cutting. To stop orreduce this, the gaps can be substantially filled with rows of hangingchains 654 or other suitable mechanical barriers that substantiallyprevent the debris from leaving the vicinity of the deck 651. The mower620 can also be provided with a bumper 655 to give the mower thecapability of pushing piles of debris or other large or tall objects, orto protect the main body of the mower from damage due to front-endcollisions with large or tall objects. Although the chains 654 and thebumper 655 may serve these functional purposes, details of their designmay also be selected to enhance the ornamental appearance of the mower.

A schematic broken-away perspective view of a portion of a mower deck751, which may be the same as or similar to the mower deck 651, is shownin FIG. 7. Three sets of mower cutting blades 752 are rotationallymounted beneath the mower deck with suitable bearings, and drive wheelslocated above the deck. The drive wheels connect to the PTO unit withone or more drive belts. The height of the blades above the grounddetermines the length of cut of the grass or other vegetation.

A schematic block diagram of a remote handheld unit (remote controlunit) 860 that can be used to control any of the mowers discussed hereinis shown in FIG. 8. The unit 860 may be the same as or similar to theunits 160 or 360 discussed above. The handheld unit 860 has a housing862 with optional handles 865, and a local x-y-z coordinate system 861as described above. Attached to or mounted on or in the housing 862 area number of electrical components (including electromechanicalcomponents and electro-optical components) that work together to givethe unit the various functional capabilities described herein. Thosecomponents may include some or all of a controller 864, a proximitydevice 866, an Enable switch 867, a battery 868, a memory 869, aninclinometer 870, a display 872, an antenna 874, an emergency stop(“E-stop”) switch 875, one or more discrete light sources 876, ajoystick 878, and one or more other user input devices 879, or othercomponents.

The controller 864 electronically controls or communicates with some orall of the other electronic system components of the handheld unit 860over wired connections. The controller 864 may be any suitable digitalelectronic controller or microcontroller, now known or later developed,that is capable of performing the tasks described herein under theenvironmental conditions typically experienced by a remote handheldunit. The controller 864 may include one or more suitable centralprocessing unit (CPU), system clock, dedicated read-only memory (ROM)and random access memory (RAM), and input/output modules, among otherfeatures and capabilities. The controller 864 may be or include a singleintegrated circuit (IC) or circuit board, or it may include multiplesuch circuit boards and ICs. The separate memory 869 may be or includenon-volatile memory, and it may store instructions such as software andfirmware which, when loaded into and carried out by the controller 864,cause the controller and handheld unit to perform the tasks describedherein. The reader will understand that an electronic engineer ofordinary skill can select the appropriate electronic components andconfigure them in such a way as to provide the controller 864 and thehandheld unit 860 with the functionality as described, without undueexperimentation.

In addition to sending control signals to the various components itmanages, the controller 864 may also receive diagnostic informationincluding sensor information or other status information from suchcomponents. Thus, the wired link(s) between the controller 864 and othercomponents it receives transducer signals from, such as the joystick878, the proximity device 866, and the inclinometer 870, may allow forboth (a) the transducer signal(s) to be sent from the component to thecontroller 864, and (b) diagnostic signals or status information to besent from the component to the controller. The diagnostic signals mayfor example include one or more fault signals generated by one or morefault sensors that may be included as part of the component, or as partof the controller 864, or as an add-on accessory. In exemplaryembodiments such a fault sensor may be or include an open circuitdetector or a short circuit detector, or both, which monitors electricalcontinuity between wires or pins of a given such component. Similardiagnostic information can be obtained by the wired connections thatcouple the controller 864 to other components on the handheld unit, suchas those that the controller sends control signals to, e.g. the display872 or light sources 876. Thus, for example, the controller 864 may haveone or more dedicated circuits or elements that monitor the electricalcontinuity of any or all of these components, and detect an electricalshort or electrical open circuit condition. The fault sensor may also beor include in some cases a voltage or current sensor, e.g. to monitoroutput characteristics of the battery 868.

The proximity device 866 may be or include a beacon, adistance-measuring device, a position-measuring device, or anycombination thereof. A beacon is simply an electromagnetic emitter thatdoes not itself measure distance or position, but whose output signalcan be used by another device, such as a second proximity device on themower, to determine distance or position. A distance-measuring devicecan determine or measure a distance to another object, such as to adistant, external beacon or a second proximity device on the mower, butcannot determine a direction to such other object, and thus it cannotdetermine the position of such other object, nor its own positionrelative to such other object. A position-measuring device can determineor measure the position of another object, such as an external beacon ora second proximity device, or the position of itself relative to suchother object, and thus it can also determine or measure the distance tosuch other object. An example of a position-measuring device is a globalpositioning system (GPS) device.

The inclinometer 870 may in some cases be omitted from the handheld unit860 unless the tilt-related capabilities described herein are ofinterest. The inclinometer 870 may be simple is in design and function,or it may be more sophisticated and complex. In some cases theinclinometer may include two or more distinct, e.g. 1-axis,inclinometers. In some cases the inclinometer may be or include a simpleswitch that is activated when a tilt angle (or a tilt angle component ina given plane) exceeds a preset angle, or a plurality of such switchesoriented along different planes of tilt, or a plurality of such switcheshaving different preset angles. In some embodiments the inclinometer 870may provide to the controller 864 an analog or digital electronic outputsignal that represents the actual tilt angle component in a given plane,or the actual net tilt angle, to a fairly high degree of precision, e.g.in increments of 1 degree, or 0.5 degrees, or 0.1 degrees. Stateddifferently, the inclinometer provides an electronic output signal thatis representative of an actual tilt angle, or one or two actual tiltangle components, and substantially continuously variable over a rangeof angles, e.g. from 0 to at least 30, 40, 50, 60, 70, or 80 degrees. Insome cases, the inclinometer 870 in the handheld unit may be the same asor similar to the inclinometer 540 in the mower. In other cases, theinclinometer 870 may be different. For example, the inclinometer 870 mayhave an output precision or resolution that is less than that of theinclinometer 540 to save costs and take advantage of the lower degree ofprecision needed for the handheld unit. For similar reasons theinclinometer 870 may be physically smaller than, and/or use lesselectrical power than, the inclinometer 540.

The antenna 874 functions—at a minimum—to emit or broadcastelectromagnetic signals 816 to the mower, whether by a direct orindirect communication link. A direct link involves detecting thehandheld-emitted signals 816 at the mower without any intermediarydetection and rebroadcast. An indirect link involves detecting at themower not the handheld-emitted signals 816 themselves, but a rebroadcastof such signals, the rebroadcast in some embodiments occurring at adifferent region of the electromagnetic spectrum than that of theoriginal signals 816. I a direct communication link is used, theantennas preferably operate in the UHF band of the electromagneticspectrum. If an indirect communication link is used (e.g. where theunits communicate via one or more communication hubs), the antennaspreferably operate in the SHE band. In any case, the handheld-emittedsignals 816 may include information relating to the status (includingchange of status) of knobs, switches, buttons, joysticks, or otherdevices (including user input devices) that are included in the handheldunit, and may specifically include handheld unit inclinometerinformation and handheld unit diagnostic information.

In many embodiments the antenna 874 not only broadcasts thehandheld-emitted signals 816 to the mower, but also detectsmower-emitted signals such as signals 114, 514 discussed above. In suchcases, the mower-emitted signals may include, for example, mowerinclinometer information and mower diagnostic information. The antenna874 is shown schematically in the figure as a single antenna structure,and so it may be, but it may also be or include two or more antennastructures, e.g. one for receiving incoming signals and one for emittingor broadcasting outgoing signals.

The display 872, if included in the handheld unit 860, displaysinformation such as status information or warnings to the user. Thedisplay 872 thus preferably is capable of presenting informationvisually in the form of alphanumeric characters, graphic symbols, orboth for the user to read or see. In some embodiments discussed below,the display 872 may display a tilt angle of the mower or a tilt-relatedindicator, such as whether the mower tilt angle is in a safe,precarious, or dangerous (unsafe) operating zone. Thus, instead of, orin addition to, displaying the actual tilt angle of the mower, thedisplay 872 may provide a numerical, symbolic, and/or color-codedindicator of the level of danger (or safety) of the mower with regard toits tilt angle. The display 872 may be of any suitable conventionaldesign. For example, the display 872 may be or include one or morebacklit or non-backlit liquid crystal display (LCD) panels.

The emergency stop (E-stop) switch 875 is preferably large in size andred in color so the user/operator can quickly and easily locate it whenthey wish to immediately stop the mower. For similar reasons the switch875 is preferably in the form of a large pushbutton which can simply behit or tapped to activate. When the user activates the switch 875, thecontroller 864 causes the antenna 874 to emit a signal 816 which thecontroller on the mower interprets as a command to turn off the engine.

With regard to user input devices such as knobs, switches, buttons(including pushbuttons), joysticks, and the like, the reader willunderstand that these terms should be given their broadest reasonableinterpretation unless otherwise indicated. The term “switch”, forexample, may include any conventional device that a user can manipulateor otherwise interact with to change an electronic state from ON to OFF,or to make electrical continuity within a circuit, or to breakelectrical continuity within a circuit, or the like. A switch may thusencompass any of a toggle switch, rocker switch, slider switch, rotaryswitch, pushbutton, or other tactile mechanical switch, as well astouch-sensitive switches including even virtual switches that may bedisplayed on a touch-sensitive screen such as the screen of atouch-sensitive electronic device.

The discrete light sources 876 may be or include one or more individualvisible LED lamps. The controller 864 may control these light sources876 to turn ON or OFF in a manner that communicates information to theuser/operator. For example, in the absence of a display 872, a givenlight source 876 may be assigned to a given warning condition, wherebythe light source being ON communicates to the user the given warningcondition. One or more of the light sources 876 may also be made toflash on or off in a meaningful sequence, e.g., one flash may indicate afirst warning condition, two flashes in rapid succession may indicate adifferent second warning condition, and three flashes in rapidsuccession may indicate a different third warning condition.

The joystick 878 may be or include a joystick of any conventionaldesign, but preferably sized to fit conveniently on the handheld unit860. The user manipulates the joystick 878 by pushing or pulling on thestick or lever to deflect it from its neutral, vertical orientation.Joystick outputs, which depend on the amount and orientation of thedeflection of the lever are fed to the controller 864, which causes theantenna 874 to emit a signals 816 which the controller on the mowerinterprets as commands to move the tracks or wheels at specified speeds,thus causing the mower to move. Deflection of the lever J can occuralong two orthogonal planes, and orientations in between, for a full 360degree azimuthal range and a more limited range of polar angles. The twodegrees of freedom of the lever J deflection translate into twoindependent joystick outputs, one corresponding to the mower's lefttrack/wheel and the other corresponding to the mower's righttrack/wheel. In an alternative but less preferred embodiment, the singlejoystick 878 can be replaced with two control sticks that each deflectin only one plane, one such control stick associated with the mower'sleft track and the other associated with the mower's right track.

The Enable switch 867, which may be or include a pushbutton, toggleswitch, etc., is a safety mechanism that provides extra protectionagainst hazards relating to the movement of the mower, or the cuttingaction of the mower blades, or both. In some embodiments of thedisclosed systems, such mower movement or cutting action (or both)cannot be initiated remotely unless the user activates the Enable switch867 within a specified time beforehand. Further details of its operationare provided below. Unlike a conventional dead-man control, the Enableswitch 867 need not be activated continuously by the user.

In preferred embodiments, an activation or attempted activation of theEnable switch 867 by the user is ignored by the mower system, i.e., thesystem operates as if the Enable switch had not been pressed, if thejoystick lever J is not in its neutral position at the time ofactivating the Enable switch. In other words, activation of the Enableswitch 867 may be recognized only if the joystick lever J is in theneutral position at the time of such activation. This methodology may becarried out by the controller 864 i.e., the controller 864 may beconfigured to emit no enable signal from the antenna 874 in thedescribed situation or, more preferably, it may be carried out by thecontroller 534, whereupon the controller 864 may emit both the enablesignal and a non-neutral joystick signal from the antenna 874, which arereceived substantially simultaneously by the controller 534 via theantenna 544 but then ignored by the controller 534.

Besides the Enable switch 867, the E-stop switch 875, and the joystick878, other user input devices 879 may also be included in the handheldunit 860. Non-limiting examples of such other devices 879 include anEngine Start switch, a PTO switch, and a Speed Setting switch (Speedswitch), any or all of which may be or include a toggle switch,pushbutton, etc. The Engine Start switch when activated by the userprompts the controller 864 to broadcast a signal 816 from the antenna874 that causes starter on the mower to start the mower engine. The PTOswitch when activated by the user prompts the controller 864 tobroadcast a signal 816 that causes the PTO unit on the mower to turn ONor OFF, thus turning the cutting action of the mower blades ON and OFF.The Speed Setting switch when activated by the user prompts thecontroller 864 to broadcast a signal 816 that causes the mower to switchfrom a lower speed setting to a higher speed setting, or vice versa.

Having now described some major features and components of mowers andhandheld units of the disclosed systems, we will now explain furtherdetails of some of those components, and how the controllers of themower and handheld unit can be configured to operate individually or incombination to carry out some unique capabilities of the disclosedsystems. Four possible modes of operation of any of the disclosed mowersystems are illustrated in the diagram of FIG. 9, along with actionboxes that explain how transitions between such modes can be achieved.The operational modes are: (1) engine OFF; (2) engine ON, PTO disabled,drive disabled; (3) engine ON, PTO disabled, drive enabled; and (4)engine ON, PTO enabled, and drive enabled.

In operational mode (1), the mower engine is OFF, i.e., not running.Since the mower engine powers both the PTO unit and the mowertracks/wheels (via the transaxles, hydraulic transmissions, etc.), thePTO unit and drive capability of the mower are also both OFF in thismode.

In operational mode (2), the mower engine is ON, but the PTO unit isdisabled, and the drive capability is also disabled. The PTO unit beingdisabled means that if the user tries to start the mower blades turningremotely by activating the PTO switch on the handheld unit, e.g., if theuser presses a button on the handheld unit that constitutes the PTOswitch, the PTO unit will not respond and will remain OFF, and the mowerblades will remain stationary. This situation can be realized in atleast two different ways: in a first way, the controller 864 of thehandheld unit can be programmed to not respond to the user's attemptedactivation of the PTO switch, i.e., to not broadcast a signal 816 fromthe antenna 874 that would cause the PTO unit on the mower to turn ON;in a second way, the controller 864 of the handheld unit may respond tothe user's action by broadcasting the signal 816 to turn the PTO unitON, but the controller 534 of the mower may be programmed to not respondto such signal 816, which would otherwise be acted upon by thecontroller 534 to turn the PTO unit ON. In any case, in this operationalmode the PTO unit is OFF, and, by the cooperative action of the twocontrollers, the user's activation of the PTO switch on the handheldunit is ineffective to activate the PTO unit.

With regard to the first way and second way discussed in the precedingparagraph, the second way may be advantageous by consolidating most orall of the logic software in the memory and controller of the mower. Onepractical advantage of such consolidation is to simplify the process ofsoftware updates: if and when updates to the logical operation of thesystem as defined by its collective software are needed, problemsassociated with users who forget or otherwise fail to update both themower and the handheld unit at the same time can be avoided by placingall such software in the electronic components of the mower, andrequiring the user to update only the software in the mower. Such anapproach can add a level of robustness and safety to the overall mowersystem. Such an approach can also simplify the operation of the handheldunit by reducing its required computational operations, and allow forreduced power consumption and longer operating times of the handheldunit, since its battery 868 typically has a much smaller capacity thanthe battery 548 of the mower,

Still with regard to operational mode (2), the drive capability beingdisabled means that if the user tries to move the mower remotely byactivating the joystick 878, e.g. by pushing the joystick lever Jforward, backward, or sideways, the tracks of the mower will notrespond, and the mower will remain stationary. As discussed above, thissituation can be realized in at least two different ways: in a firstway, the controller 864 of the handheld unit can be programmed to notrespond to the user's attempted activation of the joystick, i.e., to notbroadcast a signal 816 from the antenna 874 that would cause the mowertracks to move; in a second way, the controller 864 of the handheld unitmay respond to the user's action by broadcasting the signal 816 to movethe mower tracks, but the controller 534 of the mower may be programmedto not respond to such signal 816, which would otherwise be acted uponby the controller 534 to cause the mower tracks to turn and the mower tomove. In any case, in this operational mode the mower's drive capabilityis disabled, and, by the cooperative action of the two controllers, theuser's activation of the joystick on the handheld unit is ineffective tomove the mower.

In operational mode (3), the mower engine is ON, but the PTO unit isdisabled, and the drive capability is enabled. The PTO unit beingdisabled was already discussed above. The drive capability being enabledmeans that the user can successfully move the mower remotely byactivating the joystick 878, e.g. by pushing the joystick lever Jforward, backward, or sideways, so the tracks of the mower, and themower itself, will move. By manipulating the joystick 878, thecontroller 864 of the handheld unit is programmed to broadcast a signal816 from the antenna 874 which, when received by the controller 534 ofthe mower, causes the mower tracks to move. The cooperative action ofthe two controllers thus allows the mower to move.

In operational mode (4), the mower engine is ON, and both the PTO unitand the drive capability are enabled. The drive capability being enabledwas already discussed above. The PTO unit being enabled means that theuser can successfully turn the PTO unit ON remotely by activating thePTO switch, e.g. by pushing a button on the handheld unit thatconstitutes the PTO switch. When the PTO switch is activated, thecontroller 864 of the handheld unit is programmed to broadcast a signal816 from the antenna 874 which, when received by the controller 534 ofthe mower, causes the PTO unit to turn ON. The cooperative action of thetwo controllers thus allows the PTO unit to turn ON, thus also turningthe cutting action of the mower blades ON.

With the operational modes of FIG. 9 so defined, we can now discuss theaction boxes of that figure, which represent functions and capabilitiesof the mower system that are programmed into one or both of thecontrollers 534, 864.

At box 901 a, the user activates the Engine Start switch on the handheldunit when the system is in operational mode (1) to transition the systemto mode (2). This is of course accomplished by the controller 864broadcasting a signal 816 from the antenna 874 which, when received bythe controller 534 via the antenna 544, causes the starter 538 to startthe engine 530.

At box 901 b, the user activates the Enable switch on the handheld unitwhen the system is in operational mode (2) to transition the system tomode (4). In mode (4), full functionality of the handheld unit and itscontrols is available to the user/operator, who can remotely move andmaneuver the mower on the terrain using the joystick, and engage themower blades (and thus cut grass or other vegetation on such terrain) byactivating the PTO switch. In most cases, the majority of the time auser spends with the mower system will be spent in operational mode (4).

The disclosed mower systems can however be configured with one or morenumerous utilitarian features many of which have the effect ofincreasing the safety of, or reducing the dangers to, the user/operatoras well as possible bystanders. Consequently, the system can beconfigured to transition the system from mode (4) to one of thelower-functioning modes upon the occurrence (as determined by one orboth controllers) of any of numerous actions or conditions, some ofwhich are shown in the transition diagram of FIG. 9.

In box 901 c, the distance D between the mower and the handheld unit(see e.g. FIG. 1) is monitored by one or both controllers. When themeasured distance D is less than a stored or programmed minimum safeoperating distance (MSOD), the controller(s) disable the PTO unit so asto stop the cutting action of the mower blades. This capability preventsthe rotating mower blades from coming too close to the user/operator,who carries the handheld unit, but still allows the user to remotelymaneuver or move the mower along the terrain. In exemplary embodiments,the MSOD may be programmed to be in a range from 4 to 20 feet, or morepreferably from 7 to 12 feet.

The same transition from operational mode (4) to mode (3) can occur if amower tilt angle, such as the net mower tilt angle α measured by thecontroller 534 based on measured component tilt angles α1, α2 from theinclinometer 540, satisfies a first tilt-related condition as shown inbox 901 d. The tilt-related condition may have both an angle componentand a time component as shown, or only an angle component. For example,the tilt-related condition may be that the tilt angle (whether the nettilt angle α or one or both of the component tilt angles α1, α2) equalsor exceeds a given limit angle αLim1 for a given period of time Such acondition is not satisfied if the tilt angle exceeds αLim1 for less thanthe time T1. In a preferred embodiment, αLim1 may be 55 degrees, and T1may be 2 seconds, but other reasonable values can also be selected. Inanother example, the time requirement may be omitted, such that thecondition is satisfied if a mower tilt angle α, α1, α2 exceeds the angleαLim1 for any length of time, even momentarily.

If a transition from mode (4) to mode (3) occurs and the user/operatorwishes to restore full system functionality to mode (4), they may do soby activating the Enable switch as shown at box 901 k.

In box 901 e, the occurrence of another condition can cause the systemto transition from either mode (4) or mode (3) to mode (2), where boththe PTO and the drive capability are disabled but the engine remains ON.The condition is that no joystick activity or activation occurs for agiven period of time T2, i.e., the joystick lever is not moved from itsneutral (zero) position for the period T2, where the beginning of theperiod T2 is understood to coincide with the moment the Enable switch867 is activated. This condition may be an indication that the user haslost consciousness or encountered some other problem that prevents themfrom exercising adequate control over the mower, thus for a measure ofsafety the PTO and drive capability are shut down. Careful selection ofT2 should be made, keeping it long enough to avoid excessively frequentdrops from mode (4) down to mode (2) during normal cutting operations,but short enough to avoid placing the user or bystanders in unduedanger. In preferred embodiments T2 may be in a range from 5 to 20seconds, or about 10 seconds. As exemplified by the operation of box 901e, the mower system may treat the Enable switch 867 as if it had aresponse window limited to the time period T2. Thus, if the useractivates a PTO switch on the handheld unit within the period T2 ofactivating the Enable switch, the PTO unit will turn ON, whereas if theuser activation of the PTO switch occurs later than T2 after activatingthe Enable switch, the PTO unit will remain off. Similarly, if the useractivates the joystick 878 within the period T2 of activating the Enableswitch, the mower tracks (and the mower) will move, whereas if the useractivation of the joystick occurs later than T2 after activating theEnable switch, the mower tracks and the mower will remain stationary.

In box 901 f, loss of a wireless signal, optionally for a period of timeT3, can cause the system to transition from any of modes (2), (3), or(4) to mode (1), i.e., total shutdown of the mower. In normal operation,one or more of the handheld-emitted signals 816 discussed above istransmitted on a continuous or semi-continuous (e.g. frequently pulsed)basis from the antenna 874 to the antenna 544, or a carrier signal orstandby signal is transmitted in that manner, such that any loss of, orinterference with, the wireless signal between the handheld unit and themower can be instantly or rapidly detected and timed. In a preferredembodiment, T3 may be 2 seconds, but other reasonable values can also beselected, for example, in a range from 0.5 to 5 seconds. In anotherexample, the time requirement may be omitted, such that the condition issatisfied for even a momentary loss of the wireless signal.

Action boxes 901 g, 901 k, 901 i, 901 j, 901 k, and 901L are similar tobox 901 f insofar as the described conditions cause the system totransition from any of modes (2), (3), or (4) to mode (1), i.e., totalshutdown of the mower.

For box 901 g, the condition is the detection of a drop or jolt of thehandheld unit. Such drop or jolt may be a sign of the user/operatorfalling, or dropping the unit on the ground. This action box and relatedsystem capability is meant to protect the operator and possiblebystanders from being harmed in such an event by the active mower.Detection of the drop may be accomplished by any suitable means. In somecases, the controller 864 may monitor the output of the inclinometer 870(which measures tilt angle(s) of the handheld unit), and may interpret asudden or abrupt change in the output as a drop event to satisfy thecondition of box 901 g. In some cases, an accelerometer or other motionsensor may be included in the handheld, and the controller 864 maymonitor the output of such sensor to detect a drop event.

For box 901 h, the condition is the detection of an excessive tilt angleof the handheld unit. Such a condition may be a sign of theuser/operator losing control of the handheld unit. Detection of thiscondition may be made by the controller 864 monitoring the output of theinclinometer 870, which measures tilt angle(s) of the handheld unit. Themeasured angle(s) may be a net tilt angle α or component tilt angles α1,α2, as shown in FIG. 4. The condition of box 901 h may be satisfied whenthe tilt angle of the handheld unit exceeds a limit angle in a rangefrom 20 to 55 degrees, for example, 35 degrees. The condition may besatisfied when such a tilt angle requirement is met even momentarily, orit may also include a requirement that the tilt angle condition besatisfied for a specified period of time.

Boxes 901 i, 901 j relate to excessive mower tilt and as such may besimilar to box 901 d, except that different tilt angle and/or timelimits, which may arguably represent a greater danger to theuser/operator than those of box 901 d, are used, and except that thesystem transitions from any of modes (2), (3), and (4) to mode (1).Reference is made to the above discussion of box 901 d, which will notbe repeated again for brevity. In some cases, limit angles (ΔLim2,ΔLim3) used for one or both of boxes 9011, 901 j may be greater than thelimit angle αLim1 used for box 901 d. In some cases, time limits (T2,T3) used for one or both of boxes 9011, 901 j may be greater than thetime limit T1 used for box 901 d. In a preferred embodiment, box 9011uses a smaller limit angle αLim2, but a greater time limit T2, thanthose of box 901 d, while box 901 j uses a larger limit angle αLim3, buta smaller time limit T3, than those of box 901 d. Specific butnon-limiting exemplary values for αLim 1, αLim2, αLim3 are 55, 30, and70 degrees respectively. Specific but non-limiting exemplary values forthe time limits T1, T2, T3 are 2 sec, 20 min, and 0.5 sec respectively.

For box 901 k, the condition is the detection of a loss or drop in oilpressure for the mower engine, optionally for a defined length of timeT4. Such a condition may be a sign of engine damage or imminent enginedamage. Detection of this condition may be made by the controller 534monitoring the output of the oil pressure sensor 537 for the mowerengine 530. A sudden drop, or loss, of oil pressure causes thecontroller 534 to turn the engine 530 OFF. The controller 534 mayoptionally wait for a time period T4 before turning the engine off, andif the measured oil pressure recovers within that time period, thecondition would not be satisfied, and the controller would not shut theengine off.

For box 901L, the condition is the activation of the E-stop switch 875on the handheld unit by the user. The E-stop switch is a prominentfeature on the handheld unit and easily accessed to allow the user toquickly shut the system down for any reason. By pushing the button orother mechanism constituting the E-stop switch, the controller 864causes the antenna 874 to emit a signal 816 which the controller on themower interprets as a command to immediately turn off the engine 530.

A schematic block diagram of a mower system is shown in FIG. 10 toprovide a simple illustration of how the system operation is dependenton both a tilt angle of a mower 1020 and a tilt angle of a handheld unit1060. The mower 1020 may be the same as or similar to the mowers 120,220. 520, and 620 described above, and the handheld unit 1060 may be thesame as or similar to the units 160, 360, and 860 described above. Themower 1020 may have a first controller 1034 coupled to a PTO unit, adrive system, a first inclinometer, and a first antenna. The handheldunit 1060 may have a second controller 1064 coupled to user inputdevice(s), a second inclinometer, and a second antenna such that thesecond controller 1064 communicates with the first controller 1034 viawireless signals 1016. The first and second controllers cooperate tocontrol operation of the mower 1020 based on both a condition of thefirst inclinometer and a condition of the second inclinometer. The firstcontroller may, for example, be configured to turn the PTO unit off whenthe first inclinometer satisfies a first condition, and the firstcondition may include the first inclinometer being tilted at a tiltangle exceeding a first limit angle. The first controller may beconfigured to turn the mower engine off when the first inclinometersatisfies a second condition, and the second condition may include thefirst inclinometer being tilted at a tilt angle exceeding a second limitangle. The first controller may be configured to turn the mower engineoff when the second inclinometer satisfies a third condition, and thethird condition may include the second inclinometer being tilted at atilt angle exceeding a third limit angle.

Another capability that may be included in the disclosed mower systemsis shown in the safety interlock transition diagram of FIG. 11. In thisdiagram, an operational mode (2/3) corresponds to either one ofoperational modes (2), (3) in FIG. 9, which have been fully describedabove and need not be repeated here. The operational mode (4) from FIG.9 is split into two modes (4.1) and (4.2) in FIG. 11, the differencebetween these modes being that in mode (4.1) the PTO unit is actuallyOFF, while in mode (4.2) the PTO unit is actually ON. The PTO unit isenabled in both modes (4.1) and (4.2). With this background, FIG. 11illustrates how the mower system is configured to respond in cases wherethe PTO switch is of the type that has both a stable ON state and astable OFF state, such as with a simple toggle switch. At the time theuser activates the Enable switch (see e.g. action box 901 b in FIG. 9),the PTO switch may be physically in either the ON state of the OFFstate, and these two possibilities are explored in FIG. 11.

On the left side of the diagram, action box 110th represents the Enableswitch 867 being activated by the user when the PTO switch is in the OFFstate. In that case, to turn the PTO unit on, the user only needs toactivate the PTO switch, i.e., move it to the ON state as shown byaction box 1101 b, which transitions the system from mode (4.1) to mode(4.2).

On the right side of the diagram, action box 1101 e represents theEnable switch 867 being activated by the user when the PTO switch is(already) in the ON state. In this situation, rather than have the PTOunit immediately spring to life without the user having touched the PTOswitch, a safety interlock capability may be provided. Thus, instead ofthe action box 1101 c transitioning the system to operational mode(4.2), it transitions to mode (4.1). Then, in order to turn the PTO uniton, the user must first turn the PTO switch to the OFF state (action box1101 d), and then turn the PTO switch to the ON state (action box 1101e). Thus, the mower system will turn the PTO unit on only when the userturns the PTO switch from the OFF state to the ON state after activatingthe Enable switch.

The methodology of FIG. 11 need not be limited to the PTO switch but canalso be applied in substantially the same manner with other user inputdevices on the handheld unit 860. For example, the other user inputdevices 879 discussed in connection with FIG. 8 may include a speedswitch to regulate the speed of the mower. The speed switch may be astandard toggle switch or may otherwise be configured as a 2-stateswitch, with a defined “Fast” state and “Slow” state, to give the useradded flexibility over the control of the mower's motion. For example,with the switch in the Fast state, the mower system may allow formaximum relative track/wheel speeds of 100 (for appropriate settings ofthe joystick 878, e.g. where the joystick lever J is pushed all the wayforward in the 12 o'clock position as discussed below in connection withFIGS. 15-17, 19, and 20), whereas with the speed switch in the Slowstate at the same joystick settings, the maximum relative speed may beonly S3, where 0<S3<100, for example, S3 may be in a range from 20 to80, or 30 to 70, or 40 to 60. Thus, when the switch is in the Slowstate, all track or wheel speeds of the mower may be reduced relative tothe Fast state by a constant multiplicative factor, e.g., all Slow statespeeds may be 40%, or 50%, or 60% of their respective Fast state speeds.

The mower system may respond to the setting of such a speed switch insubstantially the same manner as with the PTO switch setting referred toin FIG. 11. Thus, for example, if the speed switch is in the Slow stateat the time the Enable switch 867 is activated, manipulation of thejoystick 878 will cause the mower to move at the slower speeds; movementat the faster speeds requires the user to then turn the speed switchfrom the Slow state to the Fast state, after which the faster speeds areallowed. On the other hand if the speed switch is in the Fast state atthe time the Enable switch 867 is activated, manipulation of thejoystick 878 will cause the mower to move at the slower speeds, not thefaster speeds in spite of the setting of the speed switch. In order forthe system to allow the faster speeds, the user must turn the speedswitch from the Fast state to the slow state (whereupon the same slowspeeds are provided), and then turn the speed switch back to the Faststate, at which time the system will then allow the faster speeds. Thus,with this technique, the mower system will allow the faster speeds onlywhen the user turns the speed switch from the Slow state to the Faststate after activating the Enable switch.

The reader is also reminded of the preferred system response discussedabove in situations where the joystick lever J is not in the neutralposition at the time the Enable switch 867 is activated. In suchsituations, the system acts as if the Enable switch had not beenactivated at all. A system so configured recognizes activation of theEnable switch only when the joystick lever J is in the neutral positionat the time of activation.

A related but independent feature of the disclosed mower systems relatesto a brake position or status and the drive system of the mower. Thebrake 547 mentioned above and shown in FIG. 5 may represent a mechanicalhand brake, or an electronically controllable brake, or one or moresensor(s) or detector(s) associated with any such brake to allow thecontroller 534 to monitor the physical brake to determine whether it isON or OFF. If the controller 534 determines that the brake is ON, thenthe controller 534 can be programmed to not activate the drive systemregardless of what other commands would otherwise be issued by either ofthe controllers. Furthermore, if the controller(s) determine(s) that thebrake is ON, it or they can prevent the drive system from being enabledeven upon activation of the Enable switch 867 and/or attemptedactivation of the joystick 878. A determination that the brake is on canthus prevent the controller 534 from supplying drive signals to theactuators 527L, 527R at least as long as the brake is determined to beON. Upon release of the brake, such that the controller 534 determinesthe brake to be OFF, operation can then return to normal. This featureadvantageously prevents the user/operator from damaging the drivesystem/brake by preventing motion of the drive wheels 524L, 524R andrelated components while the brake is ON.

FIGS. 12 to 20 relate to the joystick 878 and how the mower system canbe configured to react to a given position or orientation of thejoystick lever J in terms of the direction and speed of the left andright tracks 523L, 523R (or 623L, 623R). In a high level overview,output signals from the joystick 878, which are indicative of theorientation of the joystick lever J, are fed to the controller 864. Thesignals from the joystick 878 include two independent signal channels,which may represent, or may be transformed to represent, one channel forthe left track 523L and one channel for the right track 523R. This ispossible because the motion of the joystick lever J has two degrees offreedom, e.g., x and y, ϕ or and θ. The controller 864 then transmitsthose signals, or scaled or otherwise modified versions of them, to themower controller 534 via the antennas 874, 544, and the handheld-emittedsignals 816. The controller 534 then uses the received joystick signals(or modified versions thereof) to generate left and right drive signalsfor the actuators 527L, 527R according to the transformationalmethodologies described herein, the physical positions of the actuatorsbeing responsible for moving the respective tracks at the desired speedsby virtue of the respective hydraulic transmissions and transaxles. Notethat the conversion from raw joystick output signals to left and rightactuator drive signals can be performed entirely by the controller 864,or entirely by the controller 534, or by a combination thereof, but inany of these cases by the cooperative action of the controllers 864,534.

Thus, FIG. 12 is a schematic top view of a joystick 1278 for use on aremote handheld unit such as unit 860. The joystick 1278 may be the sameas or similar to joystick 878. The joystick has a lever J which can betipped by the user in any direction to control the motion of the leftand right tracks of the mower, hence also its direction and speed. Wemay associate a local Cartesian coordinate system with the joystick,with the y-axis pointing directly forward (i.e., to the 12 o'clockposition), the x-axis pointing to the right (i.e., to the 3 o'clockposition), and the z-axis parallel with the lever J in its neutralposition.

These three axes can be seen in the context of a tilted lever J in anarbitrary orientation in FIG. 13. As shown, the lever's orientation canbe expressed not only in terms of the x, y, and z intercepts x1, y1, z1,but also by a spherical coordinate system characterized by a polar angleϕ measured relative to the z-axis, and an azimuthal angle θ measuredrelative to the x-axis. A planar representation of the sphericalcoordinate system (ϕ, θ), along with the x- and y-axes, is shown in FIG.14. An arbitrary orientation of the joystick lever J can thus becharacterized by its spherical coordinate (ϕ, θ), where θ can range from0 to 360 degrees (or +180 to −180 degrees), and ϕ can range from 0 toϕmax, where ϕmax is the mechanical limit of the lever's deflection.Electronic output signals of the joystick 1278 include two independentsignal channels and may be provided in terms of the intercepts x1, y1,or the angles (ϕ, θ), or according to any other suitable encodingscheme.

FIG. 15 is a representation similar to that of FIG. 14 but with pairs oftrack speed arrows superimposed thereon to illustrate a straightforwardmapping function from lever orientation to left and right track speed.Three of the pairs of track speed arrows at the outer boundary (ϕ=ϕmax)are identified and labeled, with reference number 1501 a at θ=90 degrees(12 o'clock position), reference number 1501 e at θ=45 degrees (1:30o'clock position), and reference number 150th at an intermediateposition around θ=67.5 degrees, The θ=90 position corresponds to theuser pushing the lever J fully forward in an attempt to move the mowerstraight forward at maximum speed. Consequently, in the arrow pair 1501a, the left arrow (representing the speed of the left track 523L) andthe right arrow (representing the speed of the right track 523R) are ofmaximum amplitude and equal to each other, to move the mower straightahead at maximum speed.

The θ=67.5 degree position corresponds to the user pushing the lever Jslightly to the right in an attempt to maneuver the mower in a gradualright turn. Consequently, in the arrow pair 1501 b, the left arrow(representing the speed of the left track 523L) is still the samemaximum forward speed, while the right arrow (representing the speed ofthe right track 523R) has diminished to a slower forward speed. Thisdifference in forward speeds of the tracks, with the left track fasterthan the right track, causes the mower to navigate a gradual right turn.

The θ=45 degree position corresponds to the user pushing the lever Jmore to the right (to the 1:30 o'clock position) in an attempt tomaneuver the mower in a sharper right turn. Consequently, in the arrowpair 1501 e, the left arrow (representing the speed of the left track523L) is still at the same maximum forward speed, while the right arrow(representing the speed of the tight track 523R) has a zero length andis shown in FIG. 15 as a dot or point, indicating the right track isstopped. This greater difference in the speeds of the tracks causes themower to navigate a sharper right turn than that of arrow pair 1501 b.

The other arrow pairs shown in FIG. 15 are illustrated in the samefashion, with the left arrow (or dot) of each pair representing thespeed of the left track 523L, and the right arrow or dot representingthe speed of the right track 523R. Arrows directed upwards indicate apositive motion (a motion to move the mower forward), while arrowsdirected downwards indicate a negative motion (to move the mowerbackward). The length of the arrows indicate the relative speed of thetrack forward or backward, with the longest arrows indicating maximumspeed, and the shortest arrows (dots) indicating minimum speed, i.e.,zero speed. A zero turn maneuver to the right (i.e. clockwise) isrepresented at θ=0 (e.g. the joystick lever pushed fully to the right atthe 3 o'clock position), where the left track moves forward at maximumspeed and the right track moves backward at an equal (but opposite)maximum speed. Motion of the mower straight backwards at maximum speedis represented at θ=−90 or 270, at the outer boundary (o max) of thecircle. A gentle turn of the mower backwards and to the left isrepresented at θ=−67.5 degrees, and a sharper backwards turn to the leftis represented at θ=−45.

The track motions of FIG. 15 may exhibit mirror symmetry about they-axis, e.g., a gentle forward turn to the left occurs along θ=112.5degrees, a gentle backward turn to the right occurs along θ=−112.5degrees, and a zero turn to the left (i.e. counterclockwise) occursalong θ=180 degrees. A change in orientation of the joystick leverradially (with θ fixed and ϕ changing) causes the motion of each trackto monotonically increase as increases and monotonically decrease as ϕdecreases, such that at the center of the circle (ϕ=0, the neutralposition of the joystick lever) both tracks are stopped, and the moweris at rest.

Also in the mapping function of FIG. 15, the left wheel speed remainsconstant for a fixed polar angle o along the range θ=0 to 90 (forwardmotion) and θ=180 to 270 (backward motion), and diminishes monotonicallyfrom θ=0 to −45 (forward motion) and from θ=180 to 135 (backwardmotion), and increases monotonically from θ=−45 to −90 (backward motion)and from θ=135 to 90 (forward motion). The right wheel speed behaves ina similar but counterpart fashion as can be seen from the figure.

The mapping function of FIG. 15 gives the user full maneuverability andmotion control over the mower by appropriate manipulation of thejoystick 878. However, modifications of the mapping function can be madeto enhance fine control capabilities. The modifications stem from therecognition that, with regard to fine control capability of thejoystick, most users would care more about the region near θ=90 orθ=−90, i.e., near-straight-line motion and gentle turns, than the regionnear θ=0 or θ=180, i.e., near-zero turns and extremely sharp turns.Thus, if the sensitivity of the mower's motion to small changes inazimuthal angle θ could be reduced in the regions near θ=90 or −90 atthe expense of increased sensitivity in the regions near θ=0 or 180, itmay provide an overall enhancement for the user. Such an enhancement ispossible by shifting the azimuthal angle of the places at which onetrack motion is zero and the other is non-zero, which we refer to as“null points” or “corners” of the mapping function. The corners of themapping function of FIG. 15 occur at θ=45 and −45, and by symmetry at135 and −135. The sensitivity enhancement described above can beaccomplished by shifting the null points or corners to the angles θ=θ1,−θ1, 180−θ1, and 180+θ1, where θ1 is less than 45 but greater than 0, asshown in the modified mapping function of FIG. 16.

Thus, FIG. 16 presents a mapping function of joystick orientation totrack motion substantially similar to FIG. 15, except that the nullpoints or corners have been shifted to enhance fine controlcapabilities. In preferred embodiments, the reduced corner angle θ1 isin a range from 10 to 40 degrees, more preferably 20 to 30 degrees. Theincreased azimuthal range between null points in the forward direction(the range equal to 180−2*θ1, compared to 90 degrees for FIG. 15) givesthe user better fine motion control for such forward-type maneuvers thanthe approach of FIG. 15. Similarly, the increased azimuthal rangebetween null points in the backward direction (the range again equal to180−2*θ1) gives the user better fine motion control for suchbackward-type maneuvers than the approach of FIG. 15, These enhancementsin forward and reverse motion control of course come at the expense ofreduced fine motion control in the near-zero-turn regions near θ=0 and180.

FIGS. 17 and 18 illustrate the difference between the mapping functionsof FIGS. 15 and 16 in an alternative way. These figures plot therelative wheel speed (or track speed) versus the azimuthal position θ ofthe joystick, for a fixed polar angle The wheel speed axis goes from 0(stopped; no motion) to 100 (maximum forward speed), and to −100(maximum negative speed). The azimuthal angle θ (see FIGS. 13-16) goesfrom −90 to 90; operation over the remaining range from θ=90 to 180 to270 can be ascertained by symmetry. The polar angle ϕ (see again FIGS.13-16) is assumed to be its maximum value ϕmax in FIG. 17, and half ofthat value in FIG. 18,

In FIG. 17, a conventional right track response consistent with FIG. 15is shown by curve or function 1701, and a counterpart left trackresponse consistent with FIG. 15 is shown by curve or function 1702.Curve 1701 extends from a point E to D to 13. Curve 1702 extends frompoint E to A to B. A so-called corner-enhanced right track responseconsistent with FIG. 16 is shown by curve or function 1701 a, and thecounterpart corner-enhanced left track response consistent with FIG. 16is shown by curve or function 1702 a. Curve 1701 a extends from point Eto D to C to B. Curve 1702 a extends from point E to F to A to B. As canbe seen by inspection of the figure, the slope of curve 1701 a frompoint C to point B is less in magnitude than that of curve 1701 over therange from θ=θ1 to 90, indicating reduced sensitivity of the trackmotion to the joystick orientation. Likewise, the slope of curve 1702 afrom point E to point F is less in magnitude than that of curve 1702over the range from θ=−90 to −θ1, again indicating reduced sensitivityof the track motion to the joystick orientation.

FIG. 18 is substantially the same as FIG. 17 except that the polar angleϕ of the joystick lever is assumed to be halfway between the maximumvalue and the neutral position, i.e., ϕ=ϕmax/2. Because of this reducedjoystick deflection, the greatest wheel speed (track speed) achieved isonly 50 relative units. Otherwise, a conventional right track responseconsistent with FIG. 15 is shown by curve or function 1801, and acounterpart left track response consistent with FIG. 15 is shown bycurve or function 1802. Curve 1801 extends from a point E to D to B.Curve 1802 extends from point E to A to B. A so-called corner-enhancedright track response consistent with FIG. 16 is shown by curve orfunction 1801 a, and the counterpart corner-enhanced left track responseconsistent with FIG. 16 is shown by curve or function 1802 a. Curve 1801a extends from point E to D to C to B. Curve 1802 a extends from point Eto F to A to B. As can be seen by inspection of the figure, the slope ofcurve 1801 a from point C to point B is less in magnitude than that ofcurve 1801 over the range from θ=θ1 to 90, indicating reducedsensitivity of the track motion to the joystick orientation. Likewise,the slope of curve 1802 a from point F to point F is less in magnitudethan that of curve 1802 over the range from θ=−90 to 'θ1, againindicating reduced sensitivity of the track motion to the joystickorientation.

Another modification that can be made to the baseline mapping functionof FIG. 15 (or the track response curves 1701, 1702 of FIG. 17) stemsfrom the recognition that the fastest track speeds used for forwardmotions at or near θ=90 can be excessive if used for zero-turns andnear-zero turns in the region at or near θ=0. In other words, if theuser deflects the joystick lever to (ϕ=ϕmax, θ=0) to make the mowerexecute a clockwise zero-turn, or to (ϕ=ϕmax, θ=80) to make the mowerexecute a counterclockwise zero-turn, slower track speeds may be needed(relative to track speeds desired for straight forward or straightbackward motion) for the user to maintain full control over themaneuver, to prevent the mower from spinning too fast. Thus, if themaximum track speed could be reduced in the regions near θ=0 and θ=180compared to the maximum track speed at θ=90 or θ=−90, it may provide anoverall enhancement for the user. Such an enhancement, which we mayrefer to as a spin enhancement, is possible by adjusting the track speed(wheel speed) in the regions associated with the zero-turn maneuvers.

FIG. 19 plots left and right track (wheel) response curves similar tocurves 1701, 1702 of FIG. 17, but where such a spin enhancement has beenemployed to reduce the track (wheel) speed at or near θ=0 (and θ=180). Aspin-enhanced right track response is shown by curve or function 190 k,and a counterpart spin-enhanced left track response is shown by curve orfunction 1902 e. The maximum track (wheel) speed at θ=0 has been reducedfrom 100 (or −100) to a smaller value ws1 (or −ws1). The reduced speedvalue ws1 may be in a range from 30 to 70 on a relative scale where themaximum achievable track (wheel) speed is 100. Curve 190 c extends froma point F to E to D to C to B, and may be piecewise linear, or at leastmonotonic, between such points. The section from point F to E has afixed track (wheel) speed of −100. Curve 1902 c extends from point F toG to H to A to B, and may likewise be piecewise linear or at leastmonotonic between points. The section from point A to B has a fixedtrack (wheel) speed of 100. FIG. 19 thus illustrates track responsecurves in which a spin function modification has been applied to providebetter zero-turn user control.

FIG. 20 is another graph of track (wheel) response curves similar tothose of FIGS. 17-19, but which incorporate both a corner enhancement,as in curves 1701 a, 1702 a of FIG. 17, and a spin enhancement, as incurves 1901 c, 1902 c of FIG. 19. The result is acorner-and-spin-enhanced right track response 2001 d which extends frompoint F to E to D to C to B, where ws1 and θ1 have the same meanings asin FIGS. 17 and 19. The curve 2001 d may be piecewise linear, or atleast monotonic, between the points, and the section from F to E mayhave a fixed track (wheel) speed of −100. A corner-and-spin-enhancedleft track response 2002 d extends from point F to G to H to A to B. Thecurve 2002 d may be piecewise linear, or at least monotonic, betweensuch points, and the section from A to B may have a fixed track (wheel)speed of 100. A mower system programmed to respond in the fashion ofFIG. 20 to the joystick 878 may provide the reduced forward and reversesteering sensitivity associated with the corner enhancement, and thereduced turning speed of the mower associated with the spin enhancement.

As described above, remote control of the mower's motion can be achievedby the cooperative action of at least the joystick 878, the controllers864, 534, the antennas 874, 544, the handheld-emitted signals 816, andthe actuators 527L, 527R. Output signals from the joystick 878, whichare responsive to the orientation of the joystick lever J, are fed tothe controller 864. The controller 864 transmits those joystick signals,or modified versions of them, by the antenna 874 as handheld-emittedsignals 816, which are received by the controller 534 through theantenna 544. The controller 534 uses the received signals to generateleft and right drive signals for the actuators 527L, 527R. The originaljoystick signals from the joystick 878 are related to the left and rightactuator drive signals by a transfer function. The transfer function maybe applied entirely by the controller 864, or entirely by the controller534, or by a combination thereof and optionally with other systemcomponent(s), but in any case by the cooperative action of thecontrollers 864, 534.

A high level illustration of these relationships is shown in theschematic flow diagram of FIG. 21. At box 2101 a, the joysticktransducer value(s) is or are read. At box 2101 b, a transform functionis applied to the joystick values. The operation of box 2101 b may beaccomplished by one system component, such as one of the controllers864, 534, or by several system components in a sequence of steps. At box2101 c, the transformed signals are applied to inputs of the actuators527L, 527R as drive signals.

FIG. 22 is another schematic block diagram of a mower system 2210 thatshows some system elements relevant to speed control. The system 2210includes a handheld unit 2260 and a mower 2220, which may be the same asor similar to handheld units and mowers respectively discussed above.The handheld unit 2260 includes a controller 2264, which receives twochannels of joystick position information shown at boxes 2201 a, 2201 bfrom a joystick such as previously discussed joystick 878. Thecontroller 2264 may also have a wired connection to a speed switch 220k, which may be one of the other user input devices 879 discussed inconnection with FIG. 8. The speed switch 2201 e may be configured as a2-state switch, with a “Fast” state and a “Slow” state, to give the useradded flexibility over the control of the mower's motion. In someembodiments, the system 2210 may respond to the speed switch 2201 c asfollows: when the switch is in the Fast state, the transform function ofFIG. 21 is a given defined relationship, such as any of those depictedin FIGS. 15-20; but when the switch is in the Slow state, all track orwheel speeds may be reduced relative to the Fast state by a constantmultiplicative factor, e.g., all Slow state speeds may be 40%, or 50%,or 60% of their respective Fast state speeds, such that the transformfunction is also reduced accordingly. The Speed switch signal and thejoystick signals are received and optionally processed in whole or inpart by the controller 2264, which transmits the information to thecontroller 2234 via the handheld signals 2216. The controller 2234 alsoreceives PTO status information from box 2201 d and drive enable/disableinformation from box 2201 e, one or both of which may optionally becommunicated by the handheld signals 2216 from the handheld unit 2260.In any case, the controller 2234 takes the information received fromthese various sources, processes it as necessary, and provides outputsin the form of actuator drive signals 2201 f, 2201 g for the right andleft actuators to move the mower in the desired fashion as describedherein. For example, if the drive enable/disable information from box2201 e is in a “disable” state, then the actuator drive signals 2201 f,2201 g will remain neutral regardless of the other inputs, and the mowerwill remain stationary. If the Speed switch 220 k is in a Slow state,then the actuator drive signals 2201 f, 2201 g will be modified(relative to the Fast state) to cause the track (wheel) speeds to bereduced uniformly by a given factor.

According to another exemplary system feature, the speed control ortransfer function provided by the system 2210 is also dependent on thestatus of the PTO unit, i.e., whether the PTO unit is ON or OFF. Inparticular, the system may reduce the track (wheel) speeds uniformly bya given factor when the PTO unit is ON. This reduction factor may be thesame as, or greater than, or less than, the reduction factor associatedwith the Speed switch.

Thus, FIG. 23 illustrates a system response graph of relative mowerspeed (which may be the track or wheel speed of a given left or righttrack or wheel of the mower) versus the joystick polar angle for a fixedazimuthal angle 0 of 90 degrees, i.e., for the joystick lever J at the12 o'clock position. The mower speed ranges from 0 (stopped) to 100(highest achievable speed for the given track/wheel). The polar angle ofthe joystick lever ranges from 0 (neutral position) to ϕmax. The curvesshown on the graph, each of which may be mathematically linear or atleast monotonic, represent the system response for differentcombinations of the Speed switch 220 k and the PTO status 2201 d. Curve2301F, which ranges from 0 at ϕ=0 to 100 at ϕ=ϕmax, is for the Speedswitch in a Fast state, and the PTO status OFF. Curve 2301Fpto, whichranges from 0 at ϕ=0 to S2 at ϕ=ϕmax, is for the Speed switch in a Faststate, and the PTO status ON. The speed S2 may be less than 100 butgreater than 0. Curve 23015, which ranges from 0 at ϕ=0 to S3 at max, isfor the Speed switch in a Slow state, and the PTO status OFF. The speedS3 may be less than S2 but greater than 0. Curve 2301Spto, which rangesfrom 0 at ϕ=0 to S4 at ϕ=ϕmax, is for the Speed switch in a Slow state,and the PTO status ON. The speed S4 may be less than S3 but greater than0. Thus, as described. 100>S2>53>S4>0. In some embodiments, S2 can beless than S3, such that 100>S3>S2>S4>0. In other embodiments, S2 canequal 53, such that 100>S2=S3>S4>0.

Thus, the controllers 534, 864 may cooperate to reduce the speed of themower by virtue of the sensed status of the PTO unit, or by the sensedstatus of the Speed switch, or both in a cumulative fashion. Changingthe Speed switch from a Fast state to a Slow state may reduce a maximumspeed of the mower by 40%, 50%, or 60%, or by an amount in a range from20% to 80%, or 30% to 70%, or 40% to 60%. A change in status of the PTOunit from OFF to ON may likewise reduce a maximum speed of the mower by40%, 50%, or 60%, or by an amount in a range from 20% to 80%, or 30% to70%, or 40% to 60%.

Another exemplary system feature is schematically illustrated in theschematic block diagram of FIG. 24. There, a mower system 2410 includesa mower 2420 and a handheld unit 2460, which may be the same as orsimilar to other mower and handheld units respectively discussed above.The mower 2420 has a controller 2434, which measures a mower tilt angle2401 a using an on-board inclinometer as discussed above. The handheldunit 2460 also has a controller 2464, which receives information aboutthe mower tilt angle via mower-emitted signals 2414. The handheld unit2460 may also have its own inclinometer, but in some cases it may beomitted. The controller 2464 has a wired connection to a display orvisual indicator such as display 872 described above, and the controller2464 causes the tilt angle of the mower to appear on the display 872, asshown at box 2401 b. Such a display conveniently informs theuser/operator on a real-time basis of how much the mower is tilted. Thisinformation is of particular value since the operator can use it tosteer the mower away from a dangerously sloped area as the displayedslope angle gets too close to a given limit angle.

As discussed above, instead of or in addition to displaying the actualtilt angle of the mower, the display 872 may provide a numerical,symbolic, and/or color-coded indicator of a tilt angle-related parametersuch as the level of danger, or the level of safety, of the mower withregard to its tilt angle. For example, the display 872 may provide adanger value from 0 to 5, with 0 corresponding to a lowest range of tiltangle and 5 corresponding to a highest, and most dangerous, range oftilt angle. The tilt-related parameter may thus be a crude or lowresolution approximation or indication of the actual tilt angle of themower. In some cases, in addition to or instead of displaying the actualtilt angle on an alphanumeric display, such a crude approximation of thetilt angle can be displayed on the display 872 or on a series ofdiscrete light sources mounted on the handheld unit, such as thediscrete light sources 876. In one example, three such discrete sourcescan be used, and the controller 864 may illuminate only one such sourcewhen the tilt angle is in a first, lowest range, and two such sourceswhen the tilt angle is in a second, higher range, and all three suchsources when the tilt angle is in a third, highest range. In evensimpler embodiments, a single discrete light source can be used toprovide the user/operator with at least some information about themower's tilt angle. For example, the discrete light source may be orcomprise a multi-color LED bulb capable of selectively emitting at leasttwo different colors, e.g., red light or green light, or both, orcombinations of red, green, or blue light. Such a light source can becontrolled to emit, for example, green light when the mower's tilt angleis in a first, lowest range, and red (warning) light when the tilt angleis in a second, higher range, e.g., a range at or near a dangerousoperating condition as discussed in connection with FIG. 9. Related tothe operation of system 2410 of FIG. 24 is the schematic flow diagram ofFIG.

25. The flow diagram shows a process for calculating and displaying atilt angle of the mower on the remote handheld unit. In box 2501 a, twochannels of mower tilt information, such as the component tilt anglesα1, α2 discussed above, are read from an inclinometer 540 by thecontroller 534. In box 250th, the controller 534 and/or other systemcomponent(s) calculate a resultant or net tilt angle α of the mower,such as using the equation above containing the inverse sine and squareroot functions. In box 2501 c, the calculated net tilt α is transmittedwirelessly to the handheld unit. In box 2501 d, the calculated tilt a isdisplayed on the handheld unit, e.g. by the controller 2464.

Still another exemplary system feature is schematically illustrated inthe schematic block diagram of FIG. 26. This diagram shows howdiagnostic information can be shared in a mower system 2610 between themower and the handheld unit, and displayed or otherwise communicated tothe user/operator such as through a visual or auditory warning signalthat may emanate from the mower, from the handheld unit, or both.

In particular, a handheld unit 2660 collects diagnostic information onone or more of its on-board components and communicates that informationto the mower 2620 via handheld-emitted signals 2616, while the mower2620 collects diagnostic information on one or more of its on-boardcomponents and communicates that information to the handheld unit viamower-emitted signals 2614. On-board components of the handheld unit mayinclude a joystick, which may provide a first diagnostic fault indicator2601 a and a second diagnostic fault indicator 2601 b, a controller2664, and a warning device 2601 f. On-board components of the mower mayinclude right and left actuator fault indicators 2601 e, 2601 d, anengine fault indicator 2601 e, a controller 2634, and a warning device2601 g. A warning device 2601 f on the handheld unit alerts theuser/operator of a diagnostic condition that pertains to diagnosticinformation from the handheld unit, diagnostic information from themower, or both. The warning device 2601 f on the handheld unit 2660 maybe or include one or more of the discrete light source(s) 876, thedisplay 872, or a speaker or horn (not shown). The warning device 2601 gon the mower 2620 may be or include one or both of the horn 541 and thelight(s) 542.

Unless otherwise indicated, all numbers expressing quantities, measuredproperties, and so forth used in the specification and claims are to beunderstood as being modified by the term “about”. Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thespecification and claims are approximations that can vary depending onthe desired properties sought to be obtained by those skilled in the artutilizing the teachings of the present application. Not to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques. Notwithstanding that the numerical ranges and parameterssetting forth the broad scope of the invention are approximations, tothe extent any numerical values are set forth in specific examplesdescribed herein, they are reported as precisely as reasonably possible.Any numerical value, however, may well contain errors associated withtesting or measurement limitations.

The use of relational terms such as “top”, “bottom”, “upper”, “lower”,“above”, “below”, and the like to describe various embodiments aremerely used for convenience to facilitate the description of someembodiments herein. Notwithstanding the use of such terms, the presentdisclosure should not be interpreted as being limited to any particularorientation or relative position, but rather should be understood toencompass embodiments having any orientations and relative positions, inaddition to those described above.

The following is a non-limiting list of items of the present disclosure.

-   -   Item 1. A mower, comprising:    -   a frame;    -   an engine attached to the frame;    -   mower blades attached to the frame and selectively coupled to        the engine by a power takeoff (PTO) unit;    -   a controller configured to separately control the PTO unit and        the engine; and    -   an inclinometer attached to the frame and coupled to the        controller, the inclinometer providing an inclinometer output        indicative of a tilt angle of the frame;    -   wherein the controller is configured to turn the PTO unit off        but keep the engine on when the inclinometer output satisfies a        first condition, and configured to turn the engine off when the        inclinometer output satisfies a second condition.    -   Item 1.1. The mower of item 1, wherein the first condition        comprises the tilt angle exceeding a first, value, and the        second condition comprises the tilt angle exceeding a second        value greater than the first value.    -   Item 1.2. The mower of item 1.1, wherein the first condition        comprises the tilt angle exceeding the first value for a first        nonzero time interval, and the second condition comprises the        tilt angle exceeding the second value for a second time        interval, the second time interval being less than the first        time interval.    -   Item 1.3. The mower of item 1, wherein the first condition        comprises the tilt angle exceeding a first value, and the second        condition comprises the tilt angle exceeding a second value less        than the first value.    -   Item 1.4. The mower of item 1.3, wherein the first condition        comprises the tilt angle exceeding the first value for a first        nonzero time interval, and the second condition comprises the        tilt angle exceeding the second value for a second time        interval, the second time interval being greater than the first        time interval.    -   Item 1.5. The mower of item 1, wherein the first condition        comprises a first nonzero time interval and the second condition        comprises a second time interval, the second time interval being        less than the first time interval such that the second condition        can be satisfied before the first condition is satisfied.    -   Item 1.6. The mower of item 1, wherein the mower includes a        drive system controlled by the controller, and wherein the        controller is configured to keep the drive system enabled when        the inclinometer satisfies the first condition.    -   Item 1.7. The mower of item 1, further including an oil pressure        sensor mechanically coupled to the engine and electrically        coupled to the controller, and wherein the controller is        configured to turn the engine off when an output of the oil        pressure sensor satisfies a third condition.    -   Item 1.8. The mower of item 1, wherein the controller includes a        central processing unit (CPU) and a memory unit.    -   Item 1A. A mower, comprising:    -   an engine;    -   a power takeoff (PTO) unit;    -   a controller configured to separately control the PTO unit and        the engine, the controller including a central processing unit        (CPU) and a memory unit in which instructions are stored; and    -   an inclinometer coupled to the controller, the inclinometer        providing an inclinometer output indicative of a tilt angle of        the mower;    -   wherein the instructions are configured to turn the PTO unit off        but keep the engine on when the inclinometer output satisfies a        first condition, and configured to turn the engine off when the        inclinometer output satisfies a second condition.    -   Item 1A.1. The mower of item 1A, wherein the first condition        comprises the tilt angle exceeding a first value, and the second        condition comprises the tilt angle exceeding a second value        greater than the first value.    -   Item 1A.2. The mower of item 1A.1, wherein the first condition        comprises the tilt angle exceeding the first value for a first        nonzero time interval, and the second condition comprises the        tilt angle exceeding the second value for a second time        interval, the second time interval being less than the first        time interval.    -   Item 1A.3. The mower of item 1A, wherein the first condition        comprises the tilt angle exceeding a first value, and the second        condition comprises the tilt angle exceeding a second value less        than the first value.    -   Item 1A.4. The mower of item 1A.3, wherein the first condition        comprises the tilt angle exceeding the first value for a first        nonzero time interval, and the second condition comprises the        tilt angle exceeding the second value for a second time        interval, the second time interval being greater than the first        time interval.    -   Item 1A.5. The mower of item 1A, wherein the first condition        comprises a first nonzero time interval and the second condition        comprises a second time interval, the second time interval being        less than the first time interval such that the second condition        can be satisfied before the first condition is satisfied.    -   Item 1A.6. The mower of item 1A, wherein the mower includes a        drive system controlled by the controller, and wherein the        instructions are configured to keep the drive system enabled        when the inclinometer satisfies the first condition.    -   Item 1A.7. The mower of item 1A, further including an oil        pressure sensor mechanically coupled to the engine and        electrically coupled to the controller, and wherein the        instructions are configured to turn the engine off when an        output of the oil pressure sensor satisfies a third condition.    -   Item 1A.8. The mower of item 1A, wherein the mower is a slope        mower,    -   Item 1B. A method of operating a slope mower having an engine, a        power takeoff (PTO) unit, an inclinometer, and a controller        configured to separately control the PTO unit and the engine,        the method comprising:    -   turning the PTO unit off but keeping the engine on when an        output of the inclinometer satisfies a first condition, and    -   turning the engine off when the output of the inclinometer        output satisfies a second condition.    -   Item 1B.1. The method of item 1B, wherein the mower includes a        drive system controlled by the controller, and wherein the        method includes keeping the drive system enabled when the output        of the inclinometer satisfies the first condition.    -   Item 2. A mower, comprising:    -   an engine;    -   a power takeoff (PTO) unit;    -   a drive system that includes a left drive wheel, a right drive        wheel, a left actuator, and a right actuator, the left actuator        having a position that controls a speed of the left drive wheel,        and the right actuator having a position that controls a speed        of the right drive wheel;    -   a controller coupled to the PTO unit and to the left and right        actuators of the drive system;    -   wherein the controller is configured to provide first drive        signals to the first and second actuators when the PTO unit is        off, and second drive signals to the first and second actuators        when the PTO unit is on, the first drive signals characterized        by a first maximum drive speed and the second drive signals        characterized by a second maximum drive speed, the second        maximum speed being less than the first maximum speed.    -   Item 2.1. The mower of item 2, wherein the second maximum speed        is in a range from 20% to 80% of the first maximum speed.    -   Item 2.2. The mower of item 2, wherein the second maximum speed        is in a range from 40% to 60% of the first maximum speed.    -   Item 2.3. The mower of item 2, wherein the controller is also        configured to receive a joystick input and a speed switch input        independent of the PTO unit.    -   Item 2.4. The mower of item 2, wherein the mower is a slope        mower.    -   Item 2.5. The mower of item 2, wherein the controller includes a        central processing unit (CPU) and a memory unit in which        instructions are stored.    -   Item 2.6. The mower of item 2, further comprising an        inclinometer coupled to the controller.    -   Item 2.7. The mower of item 2, wherein the controller is        configured to provide control signals to the PTO unit to turn        the PTO unit on or off    -   Item 2.8. The mower of item 2, wherein the left and right        actuators are linear actuators.

Various modifications and alterations of this invention will be apparentto those skilled in the art without departing from the spirit and scopeof this invention, which is not limited to the illustrative embodimentsset forth herein. The reader should assume that features of onedisclosed embodiment can also be applied to all other disclosedembodiments unless otherwise indicated. All U.S. patents, patentapplication publications, and other patent and non-patent documentsreferred to herein are incorporated by reference, to the extent they donot contradict the foregoing disclosure.

What is claimed is:
 1. A mower, comprising: an engine; a power takeoff(PTO) unit driven by the engine; a drive system powered by the engine,the drive system including a left drive wheel, a right drive wheel, aleft actuator having a position that controls a speed of the left drivewheel, and a right actuator having a position that controls a speed ofthe right drive wheel; and a controller coupled to the PTO unit and tothe left and right actuators; wherein the controller is configured toprovide first drive signals to the first and second actuators when thePTO unit is off, and second drive signals to the first and secondactuators when the PTO unit is on, the first and second drive signalscharacterized by a. first and second maximum drive speed respectively,the second maximum drive speed being less than the first maximum drivespeed.
 2. The mower of claim 1, wherein the second maximum speed is in arange from 20% to 80% of the first maximum speed.
 3. The mower of claim1, wherein the second maximum speed is in a range from 40% to 60% of thefirst maximum speed.
 4. The mower of claim 1, wherein the controller isalso configured to receive a joystick input independent of the PTO unit.5. The mower of claim 1, wherein the controller is also configured toreceive a speed switch input independent of the PTO unit.
 6. The mowerof claim the mower is a slope mower.
 7. The mower of claim 1, whereinthe controller includes a central processing unit (CPU) and a memoryunit in which instructions are stored.
 8. The mower of claim 1, furthercomprising: an inclinometer coupled to the controller.
 9. The mower ofclaim 1, wherein the controller is configured to provide control signalsto the PTO unit to turn the PTO unit on or off.
 10. The mower of claim1, wherein e left and right actuators are linear actuators.
 11. A mower,comprising: a frame; an engine attached to the frame; mower bladesattached to the frame and selectively coupled to the engine by a powertakeoff (PTO) unit; a drive system including one or more drive wheelsselectively coupled to the engine by a transmission system; and acontroller coupled to the drive system and to the PTO unit, thecontroller including a central processing unit (CPU) and a memory unitin which instructions are stored; wherein the instructions areconfigured to modify a speed of the drive system as a function ofwhether the PTO unit is turned on or off.
 12. The mower of claim 11,wherein the drive system includes an actuator, and the controller isconfigured to actuate the actuator.
 13. The mower of claim 11, whereinthe drive system includes a transaxle powered by the engine.
 14. Themower of claim 11, wherein the controller is configured to provide afirst drive signal to the drive system when the PTO unit is off, and asecond drive signal to the drive system when the PTO unit is on, thesecond drive signal characterized by a smaller maximum drive speed thanthe first drive signal.
 15. The mower of claim 11, wherein thecontroller is configured to receive a joystick input independent of thePTO unit.
 16. The mower of claim 11, wherein the controller isconfigured to receive a speed switch input independent of the PTO unit.17. The mower of claim 11, further comprising: an inclinometer coupledto the controller.
 18. The mower of claim 11, wherein the mower is aslope mower.
 19. A method of operating a slope mower having an engine, apower takeoff (PTO) unit driven by the engine, a drive system, and acontroller, the method including determining whether the PTO unit is onor off, and automatically operating the drive system at a slower speedwhen the PTO unit is on compared to when the PTO unit is off.
 20. Themethod of claim 19, wherein the drive system includes a left actuatorand a right actuator, and wherein the automatically operating the drivesystem includes sending signals from the controller to the left andright actuators.